Control strategy of optimal distribution of feet forces for quadruped robots based on virtual model

In order to improve the dynamic walking performance of quadruped robot, a control method of optimizing feet forces distribution based on virtual model is proposed. In the supporting phase, the virtual model control method is applied to solve the virtual force of the torso. Combined with the gravity of the center of mass (CoM), the distribution problem between the virtual force of the CoM and the feet forces of the supporting legs is transformed into a quadratic programming (QP) problem, which is solved by Gurobi to realize the optimal distribution of the feet forces. Similarly, the virtual force of the swinging leg is solved by using the virtual model, and the joints torques of the robot’s swinging legs are obtained by combining the inverse dynamics feedforward of the swinging legs. Through the simulation of quadruped robot’s trot gait walking by webots and vs2019, it is verified that this method can stabilize the robot’s attitude angles and body speeds near the target values. Compared with the feet forces distribution method that abandons the lateral force control, the application of this method makes the fluctuation range of the attitude angles of the robot and the ground reaction forces (GRFs) of the supporting legs smaller. It is proved that this control method can effectively improve the walking stability and robustness of the quadruped robot.